The construction of California of slip lasted women's shoes which is used in American shoe factories today includes the preparation of an upper with a sewed-in sock lining and a sewed-on platform cover. In most of these shoes today a platform of 1/4 inch - 3/8 inch is not used as it was in the past but simply a conventional 5 or 6 iron insole consisting of a bonded fiber material such as Texon with a fiber tuck material in the shank and heel seat. The platform cover is lasted over the insole all around the shoe, creating a relatively thin platform or bead look between the upper and the outsole. After the lasting of the cover, the lasted margin of the cover is roughed and cemented with a precemented sole then attached in the normal fashion.
At the present time, the cover lasting operation is performed on roll-type side or cover lasting machines with hot melt cement being applied during the lasting operation or with the lasting cement being applied to the cover and the insole prior to lasting. When precementing is performed, the adhesive used is natural rubber latex sprayed with a spray gun onto the lasting margin portion of the insole and the upstanding lasting margin of the cover.
It has been found that the method and machine described in our United States patent application Ser. No. 529,458 can be effectively used for this type of California cover lasting with the result of increased production and/or reduction in cost with the wet latex lasting system described in United States application Ser. No. 529,458, if a primer or thin layer of compatible cement dissolved in hydrocarbon solvents is first applied to the bottom surface of the insole member and dried. This primer or adhesive can be applied to the insole board and dried in a very efficient manner prior to the die cutting of the insole blank.
The cost of the priming adhesive on the insole and its application to the insole board and the cost of the wet latex as applied by the lasting machine is far less than the cost of hot melt and gives a more flexible joint than hot melt cement.
When compared to the spraying of latex peripherally around the insole lasting margin and the upstanding lasting margin of the cover, the use of the primed insole and the wet latex machine and method materially reduces the handling and cost. With the spraying of the latex, it is necessary for an operator to pick up each shoe in turn and traverse the entire lasting margin relative to the nozzle of a treadle-actuated or trigger-actuated spray gun. To apply a uniform layer of latex in this fashion requires time and skill and requires that the shoe be stored on a rack for a sufficient length of time for the latex to dry before it can be lasted with a roll-type lasting machine.
With the precoating of the insole and direct application of wet latex to the cover during the lasting operation, this double handling and drying time is eliminated. The resulting bond of the cover to the cemented insole is the same as with the presently sprayed latex.